I'm just wondering if there is a simple way to point to an RSS feed of sermons. I haven't been able to locate that topic in any of the documentation or on a forum anywhere.
I'm not exactly sure of what the end-goal/requirements are, but here is some information to get you closer:
First, it looks like your archive url is this - http://rochesterfbc.org/sermon-category/sermons
With that, you should be able to use this url for an rss feed - http://rochesterfbc.org/sermon-category/sermons/feed
From there, I'd do a quick google search for what you are looking for exactly, since there are a few different use cases that might apply in your situation. Here is the official codex for WP - https://codex.wordpress.org/WordPress_Feeds
If there is something specific in the theme that you need help with, please let me know.